The National Retail Federation revised its holiday sales forecast last week to 3.3 percent, or $451.5 billion, up from the initial estimate of 2.3 percent.

For the most tracked shopping days of the season, "Cyber Monday" led the way, with more than $1 billion in sales, an increase of 16 percent over last year.

Thanksgiving Day online sales were up 28 percent to $407 million, and "Black Friday" improved by 9 percent.

"At this late juncture in the online holiday season, we have likely already witnessed the peak spending day of the year, which means that Cyber Monday should emerge as the season’s heaviest online spending day for the first time in history," Fulgoni said.

The research firm said that computer hardware, including Apple's iPad and laptop computers, drove most of the growth. Flat-screen televisions also helped along online sales.